Aquatic ecologist Zeb Hogan didn't hesitate before jumping (hat and all!) into Cambodia's Mekong River after a group of fishermen caught a critically endangered Mekong giant catfish earlier this month. It was the first time he'd seen the rare species in five years. 

Caught by accident near Phnom Penh, the monstrous fish was nearly seven feet (2.13 metres) long and weighed an estimated 200-250 pounds (90-114kg), a good sign for the critically endangered species. 

“It wasn’t that big for a Mekong giant catfish, but it was still larger than any catfish caught in North America over the past century,” Hogan told National Geographic. "It's exciting because it signals that the incredibly rare, endangered fish are still in the river and still making their annual spawning migration."

Once abundant, the fish have declined to just five percent of their original population. Hogan and his team chalk this up to overfishing, pollution and habitat destruction. In recent years, the building of dams along the river has also had an impact on these freshwater marvels. 

“If all their spawning grounds are above the dams, they may be driven to extinction," Hogan says. “We just don’t know.”

This month's catfish find was released in good health, but not before Hogan attached a tag to one of its fins. The hope is that fishermen in the area will report any future sightings of the fish so the team may better understand its movements – a great example of what can happen when scientists and fishermen work together.

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